Sound receiver



Sep. 2, 192%. 1,507,172-

x Y W. HAHNEMANN ET AL I SOUND RECEIVER -Filed July 21. 1921 s Sheets-Sheet 1 Sept. 2, 1924. 1,501,171

W. HAHNEMANN ET'AL SOUND RECEIVER Filed July 21. 1921 3 Sheets-Sheet 2 Sept, 2;, mm, 1,501,171

W. HAHNEMANN ET AL SOUND RECEIVER Filed July 21, 1921 5 Sheets-Shut 3 MBA- MELL'H 03 res wanna rren PTENT' Wfla;

HAHNEMANN AND HEINRICH HECHT, OF KITZEBERG, NEAR KIEL, Y ASSIGNORS T SIGNAL GESELLSCHAFT M. B. H., 01 KIEL,'GmANY.-..-

SOUND RECEIVER.

Application filed July 21,

.10 June 23, 1917, Design Patent No. 671,819;

in Germany on June 29, 1917, Design Patents Nos.671,416.and 671,417 in Germany on October 16, 1920; in France on December 21, 1920, Patent No. 537,754; inGreat Britain on January 28, 1921; and in Italy on January 31, 1921), of which the following is a specification.

This invention relates to sound receivers,

and more particularly to receivers of-this kind that serve for the reception and indication of submarine sound waves and in which the sound .wave detecting element used consists of an electromagnetic system. The invention consists in the cooperating parts of the electromagnetic system (i. e. its magnetized iron and its armature) being constructed in the form of masses joined to each other by an elastic connecting member such as a diaphragm so that a vibratory structure is formed. One of the said masses is attached to a member in the form of a diaphragm, plate, or thelike, that responds to, and takes in, sound waves fromv the sound-propagating medium, while the other 'mass ma vibrate without restraint. The magnetizing coil may be associated with any one or both of the two masses; and the manner of attaching it may be such that it is either connected to the mass itself, or held by a specialsupport and only cooperates electrically with the magnet to which it belongs.

For the reception of vsignals the diaphragm is preferably arranged to vibrate apleriodically. The construction of a diap ragm of this kind may be such that it vibrates aperiodically' either at all frequencies or at the frequencies used for signal-. ling. Aperiodicity at all frequencies may be obtained by an exceedin 1y strong damping, while to obtain aperiol licity at the signalling frequencies only, it is suificient to 1921. Serial No. 486,567.

' make the natural rate of vibration difler widely from the signalling frequency ployed.

Diaphragms that may be used for the purposes of the invention are for example such as possess a-middle portion of a comparatively large area which, at the contemplated frequencies, acts as a rigid body, and is connected to the diaphragm support .bye

marginal part which is soft or rigid in itself and elastic only at its edges; or diaphragms, which, as a whole, are profiled or stifiened by ribs from their'edges to their centers and, in addition to an elastic mar-v ginal zone, have only a very narrow elastic zone near the center which surrounds the point at which they are attached to the electromagnetic system. A vibrating medium that. impinges upon such a' diaphragm causes all points of the rigid'part, or the part attached to the electromagnetic 'system, to move equal distances back and forth along lines parallelto each other, the marginal part being deflected like a pivoted arm in a positive or negative sense. Dia

to be caused by sound waves ofany fre-. quency to execute only forced vibrations, so that they do not exhibit any pronounced natural 'note within the ra'nge of frequen-.

, phragms of this kind are specially adapted "bodies or structures which are coupled to each other, the one vibratory structure .be-

ing the magnet with its armature and the vother acting as the member for taking iii or receiving the sound waves. These. two

vibratory structures arepreferably closely coupled so that a low and a high couplin frequenc is produced in each, one of which (prefera ly the lower) is arranged to coincide with the note to be received. On account of the close coupling the natural notes of both structures may be chosen relatively high. An advantage of this is that the lower frequencies which are specially apt to interfere with sound apparatus on ships-are made less liable to affect theapparatue.

Tuned'diaphragms of any suitable form may be used in accordance with m invention; for example, such as increase in thickness from'their margins towards the center to an extent .sufiicient to give them the desired natural note, or such as are stiffened by ribs extending across them.

Various embodiments oi my invention are illustrated by way of example in the accompanying drawings. In these drawings Fig. 1 shows, in section, a receiver made in accordance with the invention, v

Fig. 2 is a view of the magnet as seen in the direction of the horizontal arrow shown,

Figs 3, 4 and 5 are similar views of a magnet whose central armatures are connected to the annular ortion of the magnet by strips. wires, an a perforated annular diaphragm respectively,

Fig. 6 is a receiver in which the form of the vibrations of the sound receiving diaphragm is determined by a rigid middle portion,

Fig. 7 is a view of the dia hragm of Fig. 6 as seen from the right in t is figure,

Fig. 8 is a receiver similar to that shown in Fig. 6 but in which the rigid middle portion of the receiving diaphragm also acts as one of the masses of the electromagnet,

Fig. 9 is a view of the diaphragm of Fig. 8,

Fig. 10 is another modified receiver of the same type and Fig. 11 a view of its diaphragm,

Fig. 12 is a section of a receiver whose diaphragm increases in thickness from the margin to the center to an extent suficient to give it the desired natural note and Fig. 13 is a similar receiver in which the desired natural note of the diaphragm is obtained by means of stiffening ribs which flare from the margin towards the center.

According to Fig. 1 the detector is arranged in a casing 1 closed by a diaphragm 2 which operates to take in the sound. Attached to this diaphragm is the armature 3 which forms a part of the electromagnet or electromagnetic system. The magnetic system is constructed in the form of a ring 4 and bends 6 and 6 which carry the coils 5, and whose free ends approach the armature 3 so as to leave a small gap and to include the armature in the magnetic circuit." The magiieticl.,system is connectedto the armature 3 by adiaphr'agm 7 fixed in the'ring 4 and thus a vibratory structure with two vibrating masses joined by an elastic member is formed. The coils 5 are connected to a telephone 8.

The direction of the magnetic lines of force is indicated by the arrows in the drawing according to which these lines emanating from the armature 3 pass into the bend 6, divide in the ring a, combine again in the lower bend 6' and pass thence back into the armature 3.

The elastic connection between the armature and the magnetic system, instead of consisting of a diphragm 7, may take other forms. hus strips 9, Fig. 3, or wires 10, Fig. 4, or the like may be employed. When diaphragms are used it is not necessa for these to be made in the form of closed ates; they may be perforated or subdivided as in ilarhe c5ase of the diaphragm 11 shown in According to Figs. 6 and'7 the sound receiving diaphragm is made up of a ri id middle part 2 and a marginal part 9 t at connects the middle part to the casing l and is stiflened by ribs 10, so that only theedges of the marginal part remain flexiblel Connected to the rigid middle parts is the magnetic system 6 to which is connected by an elastic plate 7 the armature 3 and thus forms a vibratory structure with the latter. The form of vibration executed by the diaphragm during its negative hase is indicated in the drawing by broken ines.

The modification shown in Figs. 8 and 9 differs from that of Fi s. 6 and 7 only in the fact that the rigid middle portion 2 of the diaphragm also acts as the one mass of the vibratory structure, and as the armature 3 of the electromagnet. The form of vibration of the diaphragm is the same as in Figs. 6 and 7.

No special measures would be involved if, instead of the receiving diaphragms shown in Figs. 6 to 9, a diaphragm accordin to Figs. 10 and 11 or any other equivalent iaphragm were employed.

The device shown in Figs. 10 and 11 comprises a thin diaphragm v9" stiffened throughout by radial ribs 11 in such a manner that only a narrow annular elastic zone 12 remains near its fixed peripher and another elastic ring-shaped zone 13 0 small diameter is left at the central point of attachment. The form of vibration of this diaphragm is indicated in Fig. 10 by broken ines.

The diaphragm of Fi 12 increases in thickness from the perip ery towards the center to such an extent as to give it a natural note which coincides with that of the vibratem with its armature.

.. In the case of Fig. 13 the tuning of the thin diaphragm 9' is accomplished with the aid of ribs 11 extending across it in the form of diametersat all parts of its surface and flaring in such a way as to ivc the structure a natural note which coinci es with that of the electromagnetic system with its armature.

' We claim 1. An electromagnetic sound receiver comprising; a vibratory structure consisting of two vibrating masses and an elastic member connecting the two said masses to each other, the one mass being formed of the electromagnetic system; and a sound receiv-' ing aperiodic vibrating member adapted to take in arriving sound waves and attached to one of the said masses, while the other mass is allowed to vibrate without restraint.

3. An electromagnetic sound receiver comprising; a vibratory structure consisting'of two vibrating masses and an elastic member connecting the two masses to each other, the one mass being formed of the magnet and the other of the armature of an electromagnetic system; and a sound receiving aperiodic vibrating member adapted to take in arriving sound waves, a part of this member forming one of the said masses, the

other mass being allowed to vibrate without restraint.

4. An electromagnetic sound receiver comprising); a vibratory structure consisting of two vi ratingmasses and an elastic member connecting the two said masses to each other, theone mass being formed of the magnet and the other of the armature of an elec-' tromagnetic system; and a sound receiving vibrating member adapted to take in arriving sound waves and combined with one of the said masses, while the other mass is allowed to vibrate without restraint, and the coupling between the sound receiving member and the vibratory structure being a close one.

5. An electromagnetic sound receiver comprising; a vibratory structure consisting of two vibrating masses and an elastic member connecting the two said masses to each other, the one mass being formed of the magnet and the other of the armature of an electromagnetic system; and a sound receiving aperiodic vibrating diaphragm adapted to take in arriving sound waves and attached to one of the said masses, while the other mass is allowed to vibrate without restraint, and the coupling between the receiving diaphragm and the vibratory structure being a close one. I

6. An electromagnetic sound receiver, comprising in combination, a sound receiving member; two vibratory masses formed of the electromagnetic system; and an elastic member connecting said two masses to each other; one of said masses being attached to said sound receiving member, the other being freely vibratable, and both being car ried by said member.

7. An electromagnetic sound receiver, comprising in combination, a sound receiving member; two vibratory masses formed of the electromagnetic system; one of said masses being attached to said sound receiving member'and the other being freely vibratable; and an,- elastic member connecting said masses and supporting the freely vibratable mass.

In testimony whereof we afiix our signatures in presence of two witnesses.

WALTER HAHNEMANN. HEINRICH HECHTI Witnesses: Wmmmu Renew,

GUSTAV Worms. 

